1) The pneumococcal autolysin (amidase was purified to homogeneity during the first period of this grant. Antibodies have now been made against the pure E-form amidase. These antibodies will be used in two types of experiments: a) in studies aimed at the cytochemical localization of the enzyme and, b) in biosynthetic experiments that are designed to see whether or not the E-form amidase is the precursor of the C-form enzyme. 2) Studies are in progress to dissect the metabolism of a choline containing wall teichoic acid and lipid-teichoic acid (Forssman antigen) of pneumococci. Specific metabolic inhibitors are being used in these studies. An interesting finding already made is that inhibitors of peptidoglycan synthesis cause secretion (into the medium) of teichoic acid containing macromolecular complexes. Analytical studies on these are in progress. 3) New observations were made further supporting the hypothesis that cell wall inhibitory antibiotics trigger autolysin activity in the drug-treated bacteria. Experiments are being done to understand the biochemical mechanism of this triggering effect. 4) Studies are in progress to identify the phage product and/or phage component(s) responsible for the triggering of the pneumococcal autolysin during infection with Diplophage 1.